The concurrent evaluation of brain energy state and oxygen delivery provides a unique approach to "early warning" of hypoxic/ischemic stress. Near infrared spectroscopy of oxygen delivery by hemoglobin gives an approximation to the oxygenation of the capillary bed of the cortical layers of the neonate brain. Speed of response of the optical method is high (.1 sec or less), and appropriate to sudden changes of oxygen delivery, for example, in apnea. However, the relationship between oxygen delivery and energy metabolism is uncertain. Phosphorus magnetic resonance spectroscopy gives precise and critical information of the energy state of the brain in terms of the phosphocreatine/phosphate ratio, which is in turn related to the phosphate potential (ATP/ADP x Pi) (1). The NMR method is not fast, 5 minutes may be required for a definite value, and thus, cannot serve as a fast "early warning" of hypoxic distress. The device proposed combines transcutaneous infrared spectroscopy of oxygen delivery as a rapidly responding early warning together with PMRS as a slower, but more precise, quantitative evaluation of danger. These two devices in combination can be used for the initiation of aggressive therapy by manual and automatic control of the oxygen delivery to the brain. This Phase I application has to do with tests of simplified spectrophotometric techniques for measurement of capillary bed oxygenation of hemoglobin. Two devices are described, one employing holographic grating monochromators and the other time-sharing interference filter spectrophotometry. Phase II developments include dispersive detector systems.